To the original question, I always try and move over for the leaders. Usually I know the guys beating me, and like to see them have a good race.
I'll say this though, there's a big difference between the
VERY good fast guys, and the guys who are out of control fast. I've watched alot of the real good guys, carpet, off-road whatever and they wait to make their pass. The out of control guys who fluctuate btw the A and the B depending on what guys are there are the ones who think it's their right to not let off at all and just drive right under your rear-end. I wonder if they just can't see the track well enough, or they really are just on the edge of being a bad driver with a little bit of skills..??
And I wouldn't pull out of a race either. I'll be courteous, but you never know who or when someone will crash out.